One of the best things about being a science blogger is that every day, it seems, I learn something new. I mean, I learned something new most days before I was a blogger, but now, NOW I trawl the internet looking for the things that make you go OMG. And today, I found something that is wild and weird on two different levels.
This, you guys, is the binturong.
The binturong has a couple of cool and odd things about it. The first is that it apparently smells like buttered popcorn. Something to do with their scent glands. I hear that Laelaps is all set to ferret the secret of that out, so I'm focusing on something else odd, but which is actually common to several groups of mammals: teat ownership.
Schoknect, P. "Growth and teat ownership in a litter of binturongs" Zoo Biology, 1984.
Binturongs, aka Bearcats, are closely related to civets (the ones that poop out the uber-expensive coffee), and are native to southeast Asia. They live in trees, can make cute chuckling noises when pleased, and are generally adorable. And...the babies have teat ownership.
What is teat ownership? Exactly what it sounds like. It's when you have a litter of babies, one takes top left nipple, another takes bottom right, and ne'er shall they switch. Sometimes, in an effort to switch, the babies will actually fight a little to defend their teat. Teat ownership is a behavior that is common to cats, pigs, sheep, leopards...and biturongs.
What is the point of teat sharing? The hypothesis is that teat ownership reduces fighting among littermates for the good teats (yes, there are better teats), and ensures that most teats will remain pretty equally used. But does it really reduce fighting? Other studies have shown that there are still fights among cats, pigs, etc. So what about biturongs?
So this author wired up an attractive looking nestbox with a closed circuit camera (though how much would everyone love to see baby binturongs on the internet?!?!), and got a litter of binturongs. The author observed the cubs as they grew up, and looked at who suckled where, and whether they fought about it.
Binturongs have three pairs of teats, running on either side of the chest, traditional mammal-style, but only the top two pairs were active in this case. The top are the pectoral, and the bottom are inguinal. It turned out that the cubs picked their teat, and generally stuck to it, but when given the opportunity, they would pull shenanigans or fight to get to the left rear teat. It's where all the cool baby binturongs want to be. And boy did they fight for it! Giving each other cuts and resulting in little bald patches around their baby binturong eyes. Not to mention leaving some marks on the author, who noted that after the first weighing episode, she trimmed their nails so she didn't get scratched up getting between a baby binturong and his chosen nipple.
But it turned out they were fighting over that front left for a reason.
This is a graph showing the weight of the baby binturongs. You can see that two of them really outweighed the others. Those are the cubs that got the left rear and the right rear, with the left rear as the teat of choice. And it's obvious why. The left rear and right rear cubs got substantially bigger than the others, which the author suggests means they may give better milk (higher in fat) than the other teats. And a higher fat milk supply means a bigger baby, and a healthier one. That's a nipple worth fighting over.
Schoknecht, P. (1984). Growth and teat ownership in a litter of binturongs Zoo Biology, 3 (3), 273-277 DOI: 10.1002/zoo.1430030310